Certain types of areas lend themselves to surface treatment by machine and in fact, are often treated with such machines. Examples include grassy areas such as golf courses which are treated by self propelled powers, fertilizer-spreading equipment and the like. Parking lots and other types of road surface areas are treated by being swept periodically using self-propelled machines having dirt collecting equipment mounted thereon. Still other examples of surfaces which lend themselves to treatment by machine include hard-surface floors which may be mechanically scrubbed or waxed and carpeted areas which may be vacuumed or otherwise cleaned.
Such surface treating situations often share a common characteristic. That is, the treating operation is frequently highly repetitive and involves the exercise of relatively little judgment or effort on the part of the machine operator. As an example, a particular parking lot or roadway usually is (or at least can be) uniformly swept using the same pattern time after time. About the only thing the machine operator need decide is when and in which direction to turn the machine.
However, carpeted areas in industrial and commercial establishments present a somewhat different problem in that it may not be necessary or cost effective to uniformly treat the entire carpeted area by vacuuming using the same pattern time after time and every time. That is, carpets will tend to become more heavily soiled in certain predictable areas and at a predictable rate.
Areas which become soiled at a more rapid rate include those adjacent doorways leading to and from the exterior and main traffic areas such as often-used aisles. Other areas, along walls for instance, will become only lightly soiled, even over extended periods of time. Therefore, a highly desirable surface treating strategy, the carpet vacuuming plan, will recognize such varying soiling rates and require vacuuming with frequencies keyed to such rates. The CAMP.RTM. carpet maintenance plan offered by Racine Industries, Inc. of Racine, Wisc., is such a plan.
The fact that such carpeted areas vary in soiling rates presents an opportunity for significant cost savings when vacuuming such carpeted areas. More specifically, surface treatment operations tend to be labor intensive and the cost saving opportunity lies in an ability to vacuum selected areas at selected frequencies For example, of the total cost of vacuuming large areas of carpet in a commercial setting--an office building or hospital, for example--the labor component of such total cost may be in the range of 70%.
Previous workers in this field have expressly or implicitly recognized the high labor content of such surface treating operations and have developed machines to reduce the cost of such labor. For example, U.S. Pat. No. 4,114,711 describes a floor treating machine which may be programmed to repeat a pattern of movement automatically. Programming is by first operating the machine manually and recording on a tape recorder certain signals arising from such manual operation. This "teaches" the machine the repetitive pattern to be followed. The tape is then replayed when automatic operation is desired. A distance check device provides a feedback signal of the actual distance travelled by the machine. This signal is compared with the distance programmed to have been travelled and causes the correction of slight errors.
The apparatus shown in U.S. Pat. No. 3,789,939 uses a similar approach in that a wheeled cart such as a lawnmower may be programmably controlled to follow a particular route. The route or path is initially established by operating the cart manually over the desired path to be travelled and tape recording the resulting feedback signals The cart is then expected to follow the same path in accordance with the recorded signals.
Still another approach is shown in U.S. Pat. No. 4,700,427. The machine shown therein involves automatic steering of a self propelled floor cleaning machine. One way to program the machine is to manually operate it over the area and path to be treated. Signals are simultaneously "memorized" and permit the machine to automatically follow the path thereafter. In the alternative, data is generated by automatically travelling the area to be worked, such travel being under the control of a program which stores the travelled path segments as travel occurs. Mathematical algorithms are then used to "shape" the data to minimize the total path length and/or the total working time In operation, correct execution of the command signals is monitored by transducers and telemetry equipment. Such telemetry equipment permits the detection of obstacles to activate a bypass program, causing the machine to detour around the obstacle.
Even though the machine shown in the foregoing patent is said to be operable automatically from the onset, it is clear from the specification that this initial "automatic" operation must be attended by a degree of later data modification if optimum performance is to result. In any event, the machine must be made to follow the desired path, even though "automatically," in order to permit the machine to optimally operate on the second and successive passes over the area.
These prior machines are probably effective to a degree. However, they require that the machine be first operated manually over the area to be treated or require later data modification to permit the machine to fully "memorize" and follow the desired path. If the surface area to be treated is large, as with the carpeted areas of a multi-story office building, the time required to prepare such machines for fully automatic operation is truly significant. This fact tends to detract from the cost saving advantages which may otherwise accrue from using such machines.
A machine and method for treating a selected surface area within a boundary perimeter and which uses data developed from a graphic depiction representing the surface area to be treated would be an important advance in the art. A machine and method which recognizes that in certain situations, different areas within a boundary perimeter can beneficially be treated at differing frequencies and/or using differing cleaning regimens would be equally important.